The invention relates generally to data storage systems, and in particular, to job scheduling.
In typical data storage systems, a storage controller serves as an interface between external host computers and the physical storage devices of the data storage system, and thus controls all back-end (or device-side) operations. The back-end operations can include services for I/O, such as read misses, write destaging and read prefetching. The back-end operations can also include non-I/O background operations, e.g., activities related to data copy, and other activities. The scheduling of these two classes of back-end operations, that is, I/O operations and background operations, which compete with each other for storage controller resources, has a major effect on the performance of the data storage system as a whole.